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16.6 Starting the Automatic Algorithm
During the time-out period, any command other than Sector Erase and Temporarily Stop Erase
is reset at read time, and the preceding command sequence is ignored. In the case of the
Temporary Stop Erase command, the contends of the sector are erased again and the erase
operation is completed.
Any combination and number (from 0 to 6) of sector addresses can be entered in the sector
erase buffers.
The user does not have to write to flash memory before the sector erase operation.
Flash memory automatically writes to all cells in a sector whose data is automatically erased
(preprogram). When the contents of a sector are erased, the other cells remain intact. In these
operations, flash memory does not have to be controlled externally.
The automatic sector erase operation starts from the end of the 50
µ
s time-out period after the
last Sector Erase command is written. When bit 7 is set to "1" (see "Hardware sequence flag,"
in Section 16.7, "Execution Status of the Automatic Algorithm"), the automatic sector erase
operation ends and flash memory returns to the read mode. At this time, other commands are
ignored.
The data polling function is enabled for any sector address in which data has been erased. The
time required for erasing the data of multiple sectors can be expressed as follows: time for
sector erase + time for sector write (preprogram) × number of erased sectors.
❍
Temporarily Stop Erase
The Temporarily Stop Erase command temporarily stops the automatic algorithm in flash
memory when the user is erasing the data of a sector, thereby making it possible to write data to
and read data from the other sectors. This command is valid only during the sector erase
operation and ignored during chip erase and write operations. The Temporarily Stop Erase
command (B0H) is valid only during the sector erase operation including the sector erase time-
out period. When this command is entered within the time-out period, waiting for time-out ends
and the erase operation is suspended. The erase operation is restarted when a Restart Erase
command was written. Temporarily Stop Erase and Restart Erase commands can be entered
with any address.
When a Temporarily Stop Erase command is entered during sector erase operation, the flash
memory needs a maximum of 20
µ
s to stop the erase operation. When flash memory enters
temporary erase stop mode, a Ready or Busy signal is output, bit 7 outputs "1", and bit 6 stops
to toggle. For checking whether the erase operation has stopped, enter the address of the
sector whose data is being erased and read the values of bit 6 and bit 7. At this time, another
Temporarily Stop Erase command entry is ignored.
When the erase operation stops, flash memory enters the temporary erase stop and read mode.
Data reading is enabled in this mode for sectors that are not subject to temporary erase. Other
than that, there is no difference from the standard read operation. In this mode, bit 2 toggles for
consecutive reading operations from sectors subject to temporary erase stop (see "Hardware
sequence flag," in Section 16.7, "Execution Status of the Automatic Algorithm").
After the temporary erase stop and read mode is entered, the user can write to flash memory by
writing a Write command sequence. The write mode in this case is the temporary erase stop
and write mode. In this mode, data write operations become valid for sectors that are not
subject to temporary erase stop. Other than that, there is no difference from the standard byte
writing operation. In this mode, bit 2 toggles for consecutive reading operations from sectors
that are subject to temporary erase stop. The temporary erase stop bit (bit 6) can be used to
detect this operation.
Note that bit 6 can be read from any address, but bit 7 must be read from write addresses.
To restart the sector erase operation, a Restart Erase command (30H) must be entered.
Another Restart Erase command entry is ignored in this case. On the other hand, a Temporarily
Stop Erase command can be entered after flash memory restarts the erase operation.